What's the difference between Samsung 40T and Samsung 50E batteries?

[BKW]

Considering Mten4 from ewheels:

These new mten4 shipments from ewheels will be 600wh Samsung 40T packs. Originally, the mten4 came with 750wh Samsung 50E packs.

Anyone know the difference between the two and why they chose to go down to 600wh 40T instead of keep the 750 50E packs?

Here is a direct quote from ewheels website on the 600wh batteries:

"While the new BMS architecture possesses improved safety mechanisms—temperature probes & short-protection—the hard lessons of history have demonstrated that latent fire risks may only be manifested years later. For this comparatively small machine, we deem it essential to require this model be equipped with a high-powered cell, the Samsung 40T. Beyond the safety/performance benefits, other advantages include: faster charging potential (up to 8-10A), superior pack longevity, cooler operation, increased performance, more efficient utilization of energy from the battery pack." https://www.ewheels.com/product/mten4-500-deposit/ (bottom of page)

Still, if anyone could give further information/thoughts on this subject it'd be appreciated!

[Chriull]

26 minutes ago, BKW said:

Still, if anyone could give further information/thoughts on this subject it'd be appreciated!

This wheel just has a 2 cells in parallel (20s2p).

The samsung 50e cannot really take this burden. The 40t can deliver more max and continous current.

[BKW]

2 minutes ago, Chriull said:

This wheel just has a 2 cells in parallel (20s2p).

The samsung 50e cannot really take this burden. The 40t can deliver more max and continous current.

OK thank you for your response.

Will you get less distance on the 40T than the 50E, or will they be similar?

[meepmeepmayer]

High discharge cells are a good choice on a 2p battery. Much more peak power.

You have 80% of the capacity (4000mAh 40T vs. 5000mAh 50E), and maybe you can ride them down a bit more, so I'd expect something like 15% less range (wild guess, worst case is 20% less range in line with the 20% smaller battery size). Not that range matters too much on an mten in most cases.

Edited February 8, 2023 by meepmeepmayer

[Chriull]

High discharge cells loose less capacity than high capacity cells at (higher) burdens. So there could be some "break even" burden...

Edited February 9, 2023 by Chriull

[BatteryMooch]

The Samsung 50E(2) will run for about 4% longer than the 40T(3) at 10A per cell and lower. But above that the 50E is a poor choice due to all the voltage sag you would get. For smaller packs (lower p-count) the 40T is the better choice and will give you more range even though its (nominal) capacity rating is lower.

Capacity is measured at very low current levels and this number is pretty useless for comparing cells with once you are over a few amps. What’s important is actual Wh delivered when being used since this takes into account both the capacity the cell has at higher current levels and the voltage the cell runs at. This determines how much power the ESC is actually getting.

[alcatraz]

Good point. It means that cheaper high capacity cells are best used in larger packs where we ironically don't need them as much.

And vice versa... in smaller packs there's a greater need for the high current cells (lower capacity), where we would need more capacity.

To the OP I'd like to add that there are cells like Samsung 50S that have the capacity AND high current. They cost a lot more though. For a small pack and a wealthier rider, it might still be interesting. 

[alcatraz]

If you don't take your wheel to the extremes, like low/high temperature, fast climbing/braking, heavy rider, then you'll be fine with the low amp cells.

If I were a reseller and afraid to get caught in legal issues, I'd also give everyone the high amp cells. 

[Tawpie]

or... the firmware could be aware of the cell's max recommended current draw and impose limits...

Nah, what fun would that be?

[alcatraz]

20 minutes ago, Tawpie said:

or... the firmware could be aware of the cell's max recommended current draw and impose limits...

Nah, what fun would that be?

Like that pwm-based begode firmware mod? That could work. 

[Tawpie]

2 hours ago, alcatraz said:

Like that pwm-based begode firmware mod? That could work. 

It might... but I'm more poking at KS and IM a little bit. I see little technical reason that a 16X or S18 shuts down when pushed at 31 mph, my only explanation is that they're monitoring the current pulled from the battery and just won't allow it to exceed the spec'd max draw of the cells. And they do this in firmware.

[BKW]

My tiny brain is trying to translate the speak here. I guess what this means is that the 40T cells has less voltage sag at a certain amperage than the 50E and thus can run longer at higher amps due to less voltage sag

[Tawpie]

18 minutes ago, BKW said:

My tiny brain is trying to translate the speak here. I guess what this means is that the 40T cells has less voltage sag at a certain amperage than the 50E and thus can run longer at higher amps due to less voltage sag

Pretty close. I believe the reason it could run longer is that when you're asking for current and the battery state of charge is low, the resulting voltage sag doesn't dip to the "too low to ride" level as easily with a high drain cell.

Let's say you're riding along at close to empty, cell voltages are 3.6V. Most wheels will declare "too low" when the cell voltage drops below 3.3V. If, as you're riding, you hit a bump and the system demands a quick burst of current, that burst will cause a large voltage sag in a 50E cell but a somewhat smaller sag in a 40T. The 50E may dip below the 3.3V threshold (or wherever it's set, some wheels allow down to 3.0V now) and the wheel will say "get off!" or start its low battery tiltback whereas the 40T due to its lower sag, might not drop below the threshold. This allows you (in theory) to ride further.

I don't know that it's true in practice though. I had stock high capacity cells in my S18 before replacing them with Molicels, the Molicels didn't seem to make an OMG difference at low state of charge. I personally believe this is because the LiIon chemistry's voltage falls off a cliff around 3.3V and that affects the high drain cells just as much as it does the high capacity ones. Unfortunately, I never ran 'proper' range testing with either battery, and I'm not putting the stock cells back in (I think one of the stock packs is malfunctioning, which is why they were replaced) so I won't be able to validate my belief.

"In theory, theory and practice are the same. But in practice…" (unknown)

Edited February 14, 2023 by Tawpie

[BKW]

21 minutes ago, Tawpie said:

Pretty close. I believe the reason it could run longer is that when you're asking for current and the battery state of charge is low, the resulting voltage sag doesn't dip to the "too low to ride" level as easily with a high drain cell.

Let's say you're riding along at close to empty, cell voltages are 3.6V. Most wheels will declare "too low" when the cell voltage drops below 3.3V. If, as you're riding, you hit a bump and the system demands a quick burst of current, that burst will cause a large voltage sag in a 50E cell but a somewhat smaller sag in a 40T. The 50E may dip below the 3.3V threshold (or wherever it's set, some wheels allow down to 3.0V now) and the wheel will say "get off!" or start its low battery tiltback whereas the 40T due to its lower sag, might not drop below the threshold. This allows you (in theory) to ride further.

I don't know that it's true in practice though. I had stock high capacity cells in my S18 before replacing them with Molicels, the Molicels didn't seem to make an OMG difference at low state of charge. I personally believe this is because the LiIon chemistry's voltage falls off a cliff around 3.3V and that affects the high drain cells just as much as it does the high capacity ones. Unfortunately, I never ran 'proper' range testing with either battery, and I'm not putting the stock cells back in (I think one of the stock packs is malfunctioning, which is why they were replaced) so I won't be able to validate my belief.

"In theory, theory and practice are the same. But in practice…" (unknown)

I see what you're saying. I just get confused with the terms being similar (i.e., "high capacity, "high drain", "high current"). It would be easier to translate and communicate if the terms weren't so similar. But overall, I think I understand you clearly. All this is also assuming I know how batteries work in general when I read things like "high current cells are lower capacity" -- I have to reread that a couple of times to build a picture in my tiny brain of why a current is higher at a lower capacity (less travel?)

Edited February 14, 2023 by BKW

[alcatraz]

@BKW

Take a look at the measured capacity values here:

The capacities depend on how fast you charge/discharge the cells. The 50E cells (high capacity) reach that capacity at very slow currents (left of the table). The 40T keep the capacity nearly the same even at medium currents (middle to right side of the table). 

So it means that if you have few cells sharing a certain load like on the Mten you will be to the right of the table. 

That being said. At 5A draw the 50E still have a big capacity advantage, even though they lost a bit more capacity compared to the low load scenario (left side).

[Chriull]

4 hours ago, BKW said:

All this is also assuming I know how batteries work in general when I read things like "high current cells are lower capacity" -- I have to reread that a couple of times to build a picture in my tiny brain of why a current is higher at a lower capacity (less travel?)

Current is not higher at less capacity.

Cells that are designed to max capacity (like all the 5Ah 21700 cells) cannot provide as much current. They have a higher internal resistance and hence higher voltage sag.

Cells designed for high currents have to have lower internal resistance and by the available chemistries/knowledge about battery design/or whatever else less capacity.

So by choosing a cell one has to decide between the two opposites - current or capacity.

[Seba Barcia]

Hi folks! Learning a bit here with you all, about subjects I really know very little about...
I came to check some info trying to get a better view point about the difference in the current alienRides's offered mten4's. 300wh 40T (USD849) and  750wh 50E (1.189) ...price is not the topic anyway...
I agree about "range shouldnt matter that much" speaking bout the mtens, but... Do you folks think the 40T version would be able to do a "decent amount of miles" per charge? Definitely somehow 300wh looks like going back to the AirWheel era...
I can find several uses to this wheel, but i dont wanna do always less than 10 mph "in order to be able to make it" wherever im going... 
Thanks in advance for any tip about it.... Enjoy ur rides and keep'em safe

[Tawpie]

My general advice is to buy the largest capacity battery you can afford. BUT if you're near the max weight limit of the wheel or if you like riding the wheel at its max speed or if you like really hard acceleration/braking (riding in traffic), the you should consider trading high capacity cells for high current ones (40T are high current).

That said, 300 Wh isn't going to provide fun for very long. My MTen3 has a 400 something wH battery and is 'good' for 10 miles, after that it can be a little bit sketch

Edited March 2, 2023 by Tawpie

[Chriull]

28 minutes ago, Seba Barcia said:

300wh 40T (USD849) and  750wh 50E (1.1

That's half the amount of 40t cells than 50E cells.

So half the cells in parallel gives twice the burden for the 40T.

That's unfair and not to be compared!

Imho even with 40t 300Wh could not be recommendable?

[alcatraz]

3 hours ago, Seba Barcia said:

Hi folks! Learning a bit here with you all, about subjects I really know very little about...
I came to check some info trying to get a better view point about the difference in the current alienRides's offered mten4's. 300wh 40T (USD849) and  750wh 50E (1.189) ...price is not the topic anyway...
I agree about "range shouldnt matter that much" speaking bout the mtens, but... Do you folks think the 40T version would be able to do a "decent amount of miles" per charge? Definitely somehow 300wh looks like going back to the AirWheel era...
I can find several uses to this wheel, but i dont wanna do always less than 10 mph "in order to be able to make it" wherever im going... 
Thanks in advance for any tip about it.... Enjoy ur rides and keep'em safe

The 300Wh version is just for those that need very little range.

It's not for performance purposes. At that pack size they have no choice but to go with high current cells.

A performance version would be a 600Wh high current.